Feed mechanism for rock drills



March 3, 1942.l

J. c. CUR-ris FEED MECHANIS'M FOR RocK DRILLs 3 ShIeets-Sheet` 1 Filed July 16. 1936 w a Rvs,

JOHN C. (f/@775 INVENTOR ATTORNEY March 3, 1942. J. c. cuRrls FEED MECHANISM FOR ROCK DRILLS Filed July 16, 1936 3 Sheets-Sheet 2 JOHN C, 0197/5 INVENTOR l ATTORNEY 3 Sheets-Sheet 3 March 3, 1942. J. c. CURTIS FEED MCHANISM FOR ROCK DRILLS Filed July 1e, 19:56

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ATTORNEY Patented Mar. 3, 1942 Unirse stars FEED MECHANISM FOR ROCK DRIIQLS Application July 16, 1936, Serial No. 90,951 (o1. Z55- 45) 5 Claims.

This invention relates broadly to drilling apparatus, but more particularly to a feeding mechanism for rock drills of the percussive type.

One object of this invention is to produce a rock drill with a feeding mechanism whereby feeding motion may be imparted to the drill either automatically or manually.

Another object of this invention is to produce a rock drill feeding mechanism automatically operable and equipped. with means for selectively controlling the rate of speed of the feeding motion imparted to the drill.

Another object of this invention is to produce an improved rock drill feeding mechanism of relatively simple construction, which is strong, durable, and efficient.

Other objects and advantages more or less ancillary to the foregoing and the manner in which the various objects are attained, reside in the specic construction and aggroupment of the elements peculiar to this structure, as will become apparent from a more complete examination of this specication, in the claims of which there are assembled certain specic combination of parts and specific constructionsindicative of the scope and spirit of the invention,

In the drawings:

Fig. l is a longitudinal view of a rock drill having the invention applied thereto.

Fig. 2 is an enlarged longitudinal sectional view of a portion of the feeding mechanism shown in Fig. l.

Fig. 3 is a cross sectional View taken in a plane indicated by line 3--3 in Fig. 2.

Fig. 4 is a view similar to Fig. 2 illustrating some of the parts in different position.

Figs. 5, 6, and 7 are cross sectional views taken in a plane indicated by line 5--5 in Fig. 4, and

illustrating some of the parts in diierent position.

Fig. 8 is a cross sectional View taken in a plane indicated by line 8 8 in Fig. 4.

Fig. 9 is a cross sectional view taken in a plane indicated by line 9 3 in Fig` 4.

Fig. l0 is a side elevation of one part shown in section in Figs. 2 and 4.

Fig. 11 is an end view of another part shown in section in Figs. 2 and 4.

Fig. 12 is a side elevational View of the part shown in Fig. 11.

Fig. 13 is an enlarged longitudinal sectional view of the connection between the screw and the drilling motor shown in Fig. 1.

Fig. 14 is a cross sectional view taken in a plane indicated by line lli-'I4 in Fig. 13.

latter being secured thereon against movement relative to the sh'ell by nuts 25.

Depending from the motor 23 into the shell 2|, there is the usual apertured 4lug 2B adapted' to receive a feed screw nut 21, which is formed with a head 28 shaped for engagement with the underside of the motor to prevent relative rotation therebetween. Thenut 2'| extends beyondthe rear end of the lug 26 wh'ere it is threadedexternally to receive an internally threaded sleeve ZS'engaging a lock washer 30 disposed between the sleeve and the lug '26, and thereby locking the nut 21 against longitudinal movement relative to.V the motorV Zi.` Within the sleeve 29 is disposed a bushing 3| normally free to slide therein. For locking the bushing 3| and nut 29 against relative rotation, the former is provided with a tongue 32 extending 'into an opening i formed lwithin th'e adjacent end wall of the nut 21. The bushing 3| is constantly urged toward the nut 21 by a relatively heavy compression spring 33 located within the sleeve 29.v The nut 21 and bushing 3| are internally threaded for operative engagement with a feed screw 34 which extends therethrough and has its front end journaled within a front cross h'ead 35 secured against the front end of the shell 2| by theY standard rods 23. The screw 34 is formed with a relatively small pitch causing the jars imparted to the motor to be transmitted to the screw without effecting the rotation thereof. In practice, this type of ascrew is usually called a self locking screw, and the connection including the nut and the screw is usually referred to as a self locking threaded connection. The rearend portion o-f the screw 34 extends into the housing 24 where itis slightly reduced in diameter as at 36 to 4receive the sleeve portion 31 of va driving memberv 38, which is locked thereon against Vrelative movement `by a press fit engagement and bolt 39. The sleeve portion 31 is journaled within a bushing 40 mounted within the housing 24, Y

and has its peripheral wall shaped with gear teeth 4|. The rear' end of the member 38 is cup shaped with thel peripheral wall thereof,

provided with ratchet teeth 45.

Mounted within the housing 24 in ab-utting engagement with the ring 44 and disposed coaxially therewith, there is a rotatable cam member 46 having a shank 41 protruding from the housing to receive a handle or lever 48 which is locked thereon by a key 49. The shank 41 is internally threaded to receive a cap screw 59 having a check nut 5| engaging the lever 48 for locking it against axial movement. Mounted within the lever 48 near the shank 41, there is a spring pressed plunger 52 engageable with detents formed on the housing for holding the lever in the desired position.

The cam member is formed with a counterbore 53 having a cup sh'aped Washer 54 slidable therein and accommodating a thrust ball 55 with which the inner end of the cap screw 50 is engageable. Interposed between the washer 54 and the driving member 38, there is a relatively heavy compression spring 56, the purpose of which will be explained later.

Pivctally mounted within the housing 24, there are two sets of pawls 51 and 58 engageable with the teeth v of the ring 44. For purpose of illustration, there are shown four pawls 51 capable of alternative engagement with one side of the teeth 45 and four pawls 58 alternatively engageable with the other side of the teeth 45. Each pawl has a torsional spring 59 associated therewith for constantly urging the pawl toward the ring 44. The location of the pawls within the housing 24 is such that one end portion thereof extends over the peripheral Wall of an annular bead 6B formed on the cam member 45, the diameter of this bead being somewhat greater than that of the ring 44. For a portion of its periphery, the bead 6] is provided with a cut away portion 6| of a diameter smaller than that of the root diameter of the teeth 45, thus permitting the engagement of the pawls with the teeth 45 when the former are located within the cut away portion 5|, and preventing the aforesaid engagement when the pawls are located as shown in Fig. 5, that is, in engagement with the normal peripheral wall of the annular bead B0. i i

Located within the housing 24 below the center axis of the screw 34, there is a gear 52 meshing with the teeth 4| ofthe sleeve 31. This Sear has a shaft portion 63 extending rearwardly therefrom and terminated by external splines 54. Coaxially disposed with the gear 63, there is a shaft 65 protruding from the housing 24 to receive a crank handle 66which is locked thereon against relative movement by a key 61 and nut 68. The inner end of the shaft 65 is enlarged to form intermediate the ends of the shaft an annular shoulder G9 abutting against a thrust` washer 1E); The enlarged end of the shaft 55 is also formed with external splines 1| engaging the internal splines 12 of a connecting sleeve 13 which is slidably mounted thereon, and capable of interengagementwith the splines (i4 formed on the shaft 63. .This sleeve is formed with a beveled headV 14 constantly maintained in engagement with the side wall. 15. of the cammember annular bead 6i! by a compression spring 16, which is interposed between'the. washer 1i) and head 15. This side wall 15 of the annular bead 60 is provided with a V-shaped cut away portion forming a cam 11, which the bevel head 15 of the sleeve 63 is adapted to ride for the purpose which will be explained later.

In the operation of the mechanism, let us assume that motive fluid is admitted into the drilling motor 2B for actuating its working piston which is reciprocably mounted therein. This piston, due to the reversal of its strokes, will impart jars or reciprocatory motion tothe motor 20 relative to the support 2|, which in turn is transmitted to the feed screwv 34 by the nut 21 and bushing 3|. In the present construction it will be understood that any possible axial movement of the feed screw 34 relative to the nut 21 is eliminated due to the action of the relatively heavy compression spring 33. l This spring acting on the bushing 3| constantly maintains the same in forcible engagement with one side of the screw threads 34, while the nut 21 is constantly in forcible engagement with the other side ofthe screw thread 34 by the spring 33 acting on the sleeve 29.

In the present construction, the length of 1ongitudinal movement of the feed screw is limited to the difference between the length of the ring 44 and that of the helical splined portion of the driving member 38, a distance calculated to be somewhat greater than the normal length of travel of the drilling motor resulting from the jars imparted thereto.

When the cam member 46 is positioned as shown in Fig. 5, that is, with the pawls 51 and 58 riding the normal peripheral'wall of the annular bead 6|] and thereby preventing the engagement of the pawls with the teeth 45, the reciprocatory motion of the' feed screw 34 will eiTect an oscillatory movement of the ring 44 due to the interengagement of the helical splines 42 and 43, without automati-cally effecting the rotation of the feed screwvor feeding movement of the drilling motor. During this position of the cam member 46, the head 15 of the connecting sleeve 63 is engaging the bottom of the V` shaped cam 11 thus allowing 4the connecting sleeve 6 3 to be positioned as shown in Fig. 2, that is, in operative engagement with the splines 64 of the shaft 63, and thereby connecting the crank handle 66 to the gear 62. In this instance, the gear 52 may be rotated'by manually rotating the handle 56, which rotation is transmitted at a multiplied rate of speed to the feed screw' 34 by the gear 62 meshing with'the teeth 4| of the sleeve 31, thus manually causing the feeding motion of the motor 20 due to the engagement of the nut 21 with the feed screw 34.

Wheny it is desired to effect the automatic feeding motion of the drilling motor, the lever 43 may be rotated about to position the cam member 45 as shown in Fig. 6'. During this rota-` tion of the cam member 45, the head 15 of the connecting sleeve 63 riding one side of the V- shaped cam 11 will be forced in the position shown in Fig. 4, that is out of engagement with the splines (i4 of the shaft (i3, causing thereby the disconnection of the handle 66 with the gear (-22. During the position of the cam member 43 as shown in Fig. 6, the pawls 51 are located within the cut away'portion 6|, permitting thereby the engagement of these'pawls with one side of the teeth 45, while the pawls 53 are still maintained out of engagement with the latter. During the backward longitudinal movement of the feed screw, which movement is transmitted thereto from the motor 20 by the nut 21, the helical 4splines 42 engaging the corresponding splines 43 of the ring 44 will tend to rotate the latter in a clockwise direction in Fig. 6, which rotation is prevented due to the engagement of the pawls 51 with the teeth 45, thus causing the rotation of the feed screw 34 in a counterclockwire direction in Fig. 6 and a consequential rearward feeding motion of the motor 2B additional to that normally resulting from the jars imparted to the motor. When the screw is moved forwardly by the motor through the nut 21, it will simply cause the rotation of the ring 44 in a counterclockwise direction in Fig. 6, which rotation is not prevented by the pawls 51.

If it is desired to automatically impart forward feeding motion to the motor 20, the lever 48 may be rotated to position the cam member 46 as shown in Fig. '1. In this position of the cam member, the connecting sleeve 63 is again positioned as shown in Fig. 2, while the cut away portion 6| -of the annular bead 50 is positioned to allow the engagement of the pawls 58 with the teeth 45 and prevent the engagement of the pawls 51 with the latter. In this instance, during the backward movement of the feed screw 34 transmitted thereto from the motor 20 by the nut 21, the ring 44 is free to rotate in a clockwise direction in Fig. 7, while its rotation in a counterclockwise direction normally resulting from the forward movement of the feed screw 34 is prevented by the pawls 58, thus causing the rotation of the feed screw in a clockwise direction and a consequential forward feeding motion of the drilling motor 2! additional to that n-ormally resulting from the jars imparted to the motor.

From the foregoing description, it is evident that due to the reversal of the piston strokes within the motor 28, jars or forward and backward movements are transmitted to the motor and to the screw iii. The screw thus reciprocated by the motor is automatically rotated in one or the other direction for imparting to the motor a forward or -backward movement additional to that resulting from the jars imparted thereto, thereby causing the motor to move in one direction a greater distance than in the other direction. The difference between the length of travel of the motor in one direction and its length of travel in the other direction resulting in a step by step feeding motion of the motor. It will also be understood that the automatic rearward feeding motion of the motor 2D' is responsive to the rearward longitudinal movement of the screw, and that the automatic forward feeding motion of the motor is dependent upon the forward longitudinal movement of the screw. During the rearward movement of the screw, the spring 55 is compressed by the screw, thereby accumulating energy, which is subsequently applied on the screw for effecting the forcible rotation thereof in a direction causing the forward feeding motion of the motor.

When it is desired to reduce the feeding speed of the motor, the spring 56 may be compressed by means of the cap screw E). In this instance, the spring acting on the driving member 38 will prevent a complete stroke of the latter relative to the ring 44, reducing thereby the feeding speed of the motor.

From the foregoing, it will be seen that the jars or reciprocatory motion imparted to the drilling motor and transmitted to the feed screw 34, are utilized for effecting a step by step motion of the motor in either direction. That by rotating the single lever 48 for positioning the cam member 45 as shown in Fig. 5, the operation of the power actuated mechanism is rendered ineffective while the manually operated mechanism is automatically connected with the feed screw 34. That due to the novel connection between the feed screw and the drilling motor, the reciprocatory movement of the latter is transmitted to the former without relative axial movement therebetween. That due to the effort of the compression spring 56, the feed screw is subjected to a forci-ble rotation in one direction causing thev forward feeding m-otion of the drilling motor, and that the feeding speed of the motor in both directions may be regulated by a more or less complete compression of the spring 55.

Although the foregoing description is neceswith a support, of a drilling motor slidable on the support having reciprocatory motion imparted thereto, of a feeding mechanism operatively associated with said motor and support including a duality of elements in self locking threaded engagement with each other andhaving the reciprocatory motion of said motor transmitted thereto, one of said elements being rotatable in either direction relatively to the other for effecting the forward or backward feeding movement of the motor, means associated with said rotatable element responsive to the reciprocatory motion thereof 4for effecting its rotation in either direction, and means responsive to the reciprocation of said rotatable element for feeding said motor at a greater rate of power in one `direction than in the other.

2. In a drilling apparatus, the combination with a support, of a drilling motor on the support having a reciprocatory motion imparted thereto, of a feeding mechanism for the motor including a screw carried by the support in self locking threaded engagement with the motor for reciprocation therewith and capable of rotation for imparting feeding motion to the motor, means depending upon the reciprocatory motion of said screw for effecting its rotation in either direction, means for selectively` controlling the' direction of rotation of said screw and consequently the direction of feeding motion of the motor, and means responsive to the reciprocation of said screw for feeding said motor at a greater rate of power in one direction than in the other.

3. In a drilling apparatus, the combination with a support, of a drilling motor slidable on the support having reciprocatory motion imparted thereto, of a nut carried by the motor for reciprocation therewith, a rotatable screw carried by the support in threaded engagement with said nut for reciprocation therewith, the rotation of said screw effecting the feeding motion of the motor, a duality of mechanisms connectable with said screw one for manually rotating the screw and the other for automatically rotating the screw due to the reciprocatory motion transmitted thereto by said nut, and means for selectively connecting either of said mechanisms to said screw.

4. In a drilling apparatus, the combination with a support, of a drilling motor slidable on the support having reciprocatory motion imparted thereto, of a feeding device for the motor including a duality of reciprocable elements in threaded engagement with each other, means for transmitting the reciprocatory motion of the motor to said elements, one of said elements being rotatable relative to the other for imparting feeding motion to the motor, a duality of mechanism connectable with said rotatable ele ment one for manually rotating the same and the other for automatically rotating it due 'to the reciprocatory motion thereof, and means for selectively connecting either of said mechanisms with said rotatable element.

5. In a drilling apparatus, the combination with a support, of a `drilling motor slidable on the support having reciprocatory motion imparted thereto, a screw in threaded engagement with the motor for reciprocation therewith and capable of rotation for imparting feeding motion to the motor, a mechanism manually operable for electing the rotation of said screw, another mechanism automatically operable due to the reciprocation of said screw for eiecting the rotation thereof, and means for selectively connecting either of said mechanismswith said screw.

JOHN C. CURTIS. 

